In automotive applications, more and more functions are implemented by programmable devices and associated application software rather than by dedicated circuitry. This is true for safety critical applications such as Electronic Stability Program (ESP) or airbag control and release. Proper operation is absolutely mandatory for such safety critical functions. Thus the programmable device and its associated application software must always operate properly.
Programmable devices are naturally used in common for several different applications. Switch arrays or multiplexers are used to selectively feed different input signals to the programmable device for the corresponding applications. It is mandatory for safety critical applications to ensure that the right input signals are selected by the switch array or multiplexer and fed to the programmable device. Malfunctions of the related switch control logic would result in passing other than the specified input signals through the switch array.
Hardware and software designers are today faced with the problem of how to verify that the output of the switch array or multiplexer actually corresponds to the selected input channel. To date, only plausibility checks of the selected signal(s) can determine whether the specified is proper. Plausibility checks are clearly unsatisfactory for security critical applications.
It is therefore an object of the present invention to provide an integrated programmable device which allows verification in a reliable way the correct operation of the input channel selection process.